<!doctype>
<html>
	<head>

	</head>
	<body>

	<div id="xx"></div>

		
		
		<script>
let f = (a,...b) => {
	alert(b.length)

	for(let i = 0 , j = b.length ; i < j ; i++){
		alert(b[i])
	}
}

f(1,3,4,5,6,7);
		</script>			
	</body>
</html>